Typically, elastic components used in the hygiene absorbents market are designed to have either cross direction-stretch (“CD”) only or machine direction-stretch (“MD”) only. Products with CD-stretch only are usually for the baby diaper or training pant market where as MD-stretch only products are usually required or preferred for the adult incontinence market. The reason for these two different preferred orientations is directly related to the orientation of the garment and fabric feeds during the converting and manufacturing process.
Some level of biaxial stretch may be required for the more sophisticated adult incontinence garments. In adult incontinence garments, in order to maintain leakage protection, the product needs to fit comfortably with a high level of conformity over a large area around the waist, abdomen, lower back, and crotch. In order to do this the fabrics need to be able to stretch around the user's waist as well as to offer some stretch vertically along the torso of the user.
A unique approach to manufacturing a single fabric that combines both an elastic core with an aesthetically pleasing and extensible outer cover is to meltspin relatively high molecular weight elastomers to provide adequate elasticity and provide at least one softer outer cover or “facing” layer bound to the elastic fabric to form a laminate. The layered fabric construction would be biaxially elastic, making it more challenging to use the fabric in various hygiene converting processes owing to the force required to unroll and feed the fabric into the machine which can cause potential dimensional changes, narrowing/necking of the fabric, making the manufacturing process more challenging. It is much preferred in certain articles to have the fabric elastic in only one direction and non-elastic in the other direction.
To overcome the converting challenges posed by biaxially elastic fabrics, the inventor has found that calendaring can be utilized to introduce inelastic zones in the fabric. The orientation as well as the number, spacing, size and pattern of these calendared zones can be used to create CD-stretch only, MD-stretch only or combinations of both resulting in controlled levels of biaxial stretch.
A further advantage to this process is that it can enable the creation of “deadzones” or larger inelastic zones in the fabric. The importance of these in-elastic zones is that it allows the elastic wings and “ears” in baby diapers or side panels in training pants, or even in certain adult incontinence garments, to be more robustly attached to the chassis, as well as providing an attachment point for the hook/diaper fastening system. Without deadzones, concerns exist that creep and shear of the elastic fabric could occur adjacent to the attachment point to the chassis or hook which could cause issues with fit and function of the garment, resulting in increased leakage or failure of the garment to remain in place on the baby or adult.
Relevant prior publications include U.S. Pat. No. 6,465,073 and U.S. Pat. No. 6,717,028.